2-dimensional and 3-dimensional image display device and method of manufacturing the same

ABSTRACT

A 2-dimensional and 3-dimensional image display device and a method of manufacturing the same is described. The display device includes an image display panel for displaying an image, and a switching panel having upper and lower substrates with a liquid crystal layer interposed therebetween. A pixel electrode, and first and second common electrodes, are formed on the lower substrate of the switching panel.

This application claims the benefit of Korean patent applicationP05-0131706, which was filed on Dec. 28, 2005, and is incorporatedherein by reference.

TECHNICAL FIELD

The present application relates to a display device and a method formanufacturing the same. In particular, a 2-dimensional and 3-dimensionalimage display device is described in which a color change over a rangeof viewing angles is small.

BACKGROUND

There is a need for a display device capable of displaying 3-dimensionalimages. Such a display device may be used as a new media in anadvertising field, a home 3-dimensional multimedia image displayterminal, an image display terminal for simulation andeducation/training, a visualization image display terminal for precisemeasurement and diagnosis, a medical 3-dimensional image displayterminal, a 3-dimensional image monitor for video conference andadvertisement, a 3-dimensional television for broadcasting, an imagedisplay terminal for education/entertainment, manufacturing parts forvarious kinds of special environments, an image device for 3-dimensionalgame, various heads-up displays for airplanes and vehicles, or the like.

Methods of displaying 3-dimensional images may be classified into twotypes: a 2-viewpoint type, and a multiple viewpoint type. The2-viewpoint type displays respective images for left and right eyes oneby one, whereas the multiple viewpoint type displays a binocularparallax image in wide variety of directions. In case of the multipleviewpoint type, a resolution decreases in proportion to the number ofviewpoints, whereas a degree of freedom of viewing position is higher,so that it is possible to naturally see the 3-dimensional image.

As a method of focusing the image data for left and right eyes on theleft and right eyes, respectively, a parallax barrier method, alenticular method or the like are used.

FIG. 1 is an exploded perspective view of a related art display devicecapable of displaying 2-dimensional and 3-dimensional images, and FIG. 2is a schematic view illustrating display of the 3-dimensional imageusing the related art display device of FIG. 1.

A liquid crystal display (LCD) device for displaying a 3-dimensionalimage using a parallax barrier panel 3 is provided with a backlight unit1, an image display panel 5 for displaying an image by light generatedfrom the backlight unit 1, The parallax barrier panel 3 is disposedbetween the backlight unit 3 and the image display panel 5.

The image display panel 5 is has an upper substrate on which a colorfilter layer is formed, and a lower substrate on which a thin filmtransistor (TFT) as a switching device and a pixel electrode are formed.A liquid crystal layer is interposed between the upper and lowersubstrates.

The parallax barrier panel 3 utilizes the principle of binocularparallax between left and right eyes, which makes it possible to see theimage 3-dimensionally. As shown in FIG. 2, image data for the left eyeand image data for the right eye are inputted into the image displaypanel 5 (minimally, two viewpoints). It is possible to see the2-dimensional image as a 3-dimensional image by intentionally focusingleft and right eye images on an observer's left and right eyes,respectively.

That is, by inputting two image data on sets a screen and producing leftand right eye images separately focused on the left and right eyes,respectively, the 2-dimensional plane image can be perceived as a3-dimensional image.

The parallax barrier panel 3 is divided into a plurality of areas 4 afor propagating the light toward an observer's left eye, and a pluralityof areas 4 b for propagating the light toward an observer's right eye.

Assuming that a distance between the left and right eyes is about 65 mmand a distance within which the observer can see the image ranges from25 cm to 30 cm, for example, the parallax barrier panel 3 should bedesigned such that the left and right images are focused on the left andright eyes, respectively, within distances the in range of 25 cm to 30cm from the image display panel 5.

However, the parallax barrier panel 3, which is used as a switch panel,generally uses a twisted nematic (TN) mode liquid crystal panel in whicha common electrode is disposed on an upper substrate and a pixelelectrode is disposed on a lower substrate. The viewing angle is quitenarrow and a color change becomes large over a range of viewing anglesof the 3-dimensional image (see FIG. 9A).

The response speed of a liquid crystal is slow in response to anelectric field in the TN mode switching panel, and this also limits thequality of the display.

SUMMARY

A 2-dimensional and 3-dimensional image display device is described. Anelectrode structure of a switching panel is modified into an in-planeswitching (IPS) mode structure or a fringe field switching (FFS) modestructure, in which a pixel electrode and a common electrode are formedon a lower substrate thereof.

A display device includes an image display panel for displaying animage, a switching panel including upper and lower substrates with aliquid crystal layer interposed therebetween. A pixel electrode, andfirst and second common electrodes are formed on the lower substrate. Abacklight unit for supplying light to the image display panel and theswitching panel may also be provided. In another aspect, a method ofmanufacturing a display device includes forming a first common electrodeon a substrate; forming a first protective layer on the substrate onwhich the first common electrode is formed; forming a second commonelectrode on the first protective layer; forming a second protectivelayer on the substrate on which the second common electrode is formed;forming a pixel electrode on the substrate on which the secondprotective layer is formed; forming an alignment layer on the substrateon which the pixel electrode is formed, and rubbing the alignment layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a related art display devicecapable of displaying 2-dimensional and 3-dimensional images.

FIG. 2 is a schematic view illustrating display of a 3-dimensional imageusing the related art display device of FIG. 1;

FIG. 3 is a schematic view illustrating a structure of a 2-dimensionaland 3-dimensional image display device;

FIG. 4 is a schematic view illustrating a transmissivity characteristicof the display device acting as a switching panel;

FIGS. 5A and 5B are schematic views illustrating a structure of a pixelelectrode of the switching panel;

FIG. 6 is a schematic view illustrating characteristic of transmissivitychange responsive to a voltage applied to the switching panel;

FIGS. 7A to 7C are schematic views illustrating a common electrodestructure;

FIG. 8 is a schematic view how the switching panel forms a parallaxbarrier pattern;

FIG. 9A is a graph illustrating a color change versus a viewing anglewhen using the related art switching panel; and

FIG. 9B is a graph illustrating a color change versus a viewing anglewhen using the switching panel of FIG. 3.

DETAILED DESCRIPTION

Exemplary embodiments may be better understood with reference to thedrawings, but these examples are not intended to be of a limitingnature. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

When a specific feature, structure, or characteristic is described inconnection with an example, it will be understood that one skilled inthe art may effect such feature, structure, or characteristic inconnection with other examples, whether or not explicitly stated herein.

A 2-dimensional and 3-dimensional image display device shown in FIG. 3includes an image display panel 126, a switching panel 130 acting as aswitch for producing a 3-dimensional image, and a backlight unit 100 forsupplying light to the switching panel 130 and the image display panel126. The backlight unit 100 may be configured with a light guide plate123, a lamp 120, a reflective plate 122 and a diffuser plate 128 fordiffusing light.

The image display panel 126 may have a first substrate 146 and a secondsubstrate 142 facing each other with a first liquid crystal layer 144interposed therebetween, wherein first 148 and second 140 polarizingplates are disposed on outer surfaces of the first and second substrates146 and 142, respectively.

The first substrate 146 may be a color filter substrate where red, greenand blue color filter layers may be formed on a glass substrate. Thesecond substrate 142 may be a thin film transistor (TFT) substrate wherea TFT switching device and a pixel electrode are formed on the glasssubstrate.

The image display panel 126 of the present invention may have astructure such as a twisted nematic (TN) mode and a vertical alignment(VA) structure in which a common electrode is disposed on the colorfilter substrate and the pixel electrode is disposed on the TFTsubstrate. Alternatively, the image display panel 126 may have astructure such as an in-plane switching (IPS) mode and a fringe fieldswitching (FFS) mode structure in which the pixel electrode and thecommon electrode coexist on the TFT substrate.

The switching panel 130, which acts as a parallax barrier may have athird substrate 138 and a fourth substrate 136 facing each other with asecond liquid crystal layer 132 interposed therebetween, wherein thesecond polarizing plate 140 is attached on an outer surface of the thirdsubstrate 138 and a third polarizing plate 134 is attached on the fourthsubstrate 134. The second polarizing plate 140 acts as the polarizingplate for both the image display panel 126 and the switching panel 130,and maintains a separation gap between the image display panel 126 andthe switching panel. The third substrate 138 of the switching panel 130may be formed of a glass material, and the fourth substrate 136 has theIPS mode structure or the FFS mode structure in which the pixelelectrode and the common electrode are formed.

The common electrode may be divided into a first common electrode and asecond common electrode and the respective electrodes formed ondifferent layers. The first and second common electrodes may be formedsuch that edge areas thereof are overlapped with each other.

The switching panel 130 may have two switched states: a full white statewhere light passes through when all regions are transmissive regions;and, a state where a parallax barrier pattern is formed by blocking thetransmissive region of a specific portion of the switching panel 130.

FIG. 4 is a schematic view illustrating transmissivity characteristic ofthe display device. The switching panel 130 may be disposed between theimage display panel 126 and the backlight unit 100.

The switching panel is configured such that the third substrate 138 andthe fourth substrate 136, are disposed opposite to each other, and thesecond liquid crystal layer 132 is interposed therebetween. A firstcommon electrode 153 a and a second common electrode 153 b may be formedon the fourth substrate 136. A first protective layer 152 a is formed onthe first common electrode 153 a and a second protective layer 152 b isformed on the second common electrode 153 b. A pixel electrode 151formed of a transparent conductor is disposed on the second protectivelayer 152 b. The first common electrode 152 a, the second commonelectrode 153 b and the pixel electrode 151 are formed on differentlayers, and the first and second common electrodes 153 a and 153 b arepartially overlapped with each other so that they are not spaced apartfrom each other in a plan view.

The first and second common electrodes 153 a and 153 b are formed atransparent conductor similarly to the pixel electrode 151A distance d1is a width of the pixel electrode 151, and a distance d2 is a separationdistance between the pixel electrodes 151. In another aspect, the firstand second common electrodes 153 a and 153 b are formed of a opaqueconductive material such as a metal. The backlight may be omitted.

Since there is no separation distance between the common electrodes 153a and 153 b in a plan view, a degradation of transmissivity does notoccur between the common electrodes 153 a and 153 b.

FIG. 4 also illustrates a transmissivity curve measured across aboundary area between the first and second common electrodes 153 a and153 b. The transmissivity of this arrangement is shown by the solid lineand is substantially constant. However, the transmissivity (T) may bedegraded in a region where the first and second common electrodes 153 aand 153 b are spaced apart from each other by a predetermined distancein a plan view. This response is shown as the dashed line in FIG. 4.(The corresponding structure is not shown).

The first and second common electrodes 153 a and 153 b of this exampleare partially overlapped with each other so that there is no separationdistance therebetween in a plan view.

The switching panel 130 may be manufactured by attaching the thirdsubstrate 138 and the fourth substrate 136 to each other, and the secondliquid crystal layer 132 interposed therebetween. The third and fourthsubstrates 138 and 136 may be formed, for example, of a glass material.

After depositing a conductive layer on the fourth substrate 136 actingas the lower substrate, the conductive layer may be etched to form thefirst common electrode 153 a. Afterwards, the first protective layer 152a is formed on the fourth substrate 136 having the first commonelectrode 153 a.

After depositing a conductive layer on the fourth substrate 136 wherethe protective layer 153 a has been formed, the conductive layer isetched into a predetermined shape so as to form the second commonelectrode 153 b such that it is partially overlapped with the edgeportion of the first common electrode 153 a.

After forming the second common electrode 153 b, the second protectivelayer 152 b is formed on the fourth substrate 136. Subsequently, atransparent conductive layer is deposited and etched to form the pixelelectrode 151.

The first and second common electrode 153 a and 153 b may be formed ofthe same transparent material as the pixel electrode 151 or formed ofopaque metal

The pixel electrode and the common electrode coexist on the lowersubstrate so that it is possible to embody full-white state uniformly inwide range of viewing angles, or to form the parallax barrier pattern,having a wide viewing angle characteristic.

The light generated from the backlight unit 100 can be uniformlytransmitted in a wide viewing angle range when the display devicebecomes a full-white state for displaying the 2-dimensional image.

By changing the structure of the pixel electrode 151 of the switchingpanel 130, the transmissivity characteristic may be enhanced so that itis possible to reduce the color change over a range of viewing angles.

FIGS. 5A and 5B are schematic views illustrating a structure of a pixelelectrode of the switching panel. The pixel electrode pattern of theswitching panel may be formed such that it maintains a predeterminedtilt angle. That is, the pixel electrode of the switching panel may bepatterned to maintain a predetermined angle θ with respect to analignment direction of an alignment layer formed on the lower substrateof the switching panel. The pixel electrode 151 may be formed in shapeof parallel or perpendicular pattern along a pixel area.

FIG. 5A illustrates a case where the pixel electrode 151 is patternedsuch that it is aligned in a perpendicular direction, and FIG. 5Billustrates a case that the pixel electrode 151 is patterned such thatit is aligned in a parallel direction.

The pattern of the pixel electrode 151 may have a tilt angle in range of1° to 20° with respect to the alignment direction of the alignmentlayer, and the transmissivity characteristic may be optimum when thetilt angle ranges from 3° to 5°. However, the angle for the optimumtransmissivity characteristic may vary according to the size of thepanel, the liquid crystal, the electrode width, and the distance betweenthe electrodes.

FIG. 6 is schematic view illustrating characteristic of transmissivitychange in response to a voltage applied to the switching panel. Thetransmissivity characteristics of respective common electrode regions towhich the electric field is applied and not applied are shown.

When the light is transmitted in a region corresponding to one commonelectrode but is blocked in a region corresponding to the other commonelectrode, the parallax barrier pattern is formed so that it is possibleto view the 2-dimensional images as the 3-dimensional image.

The driving characteristic of the switching panel may be expressed as aas Vcomp=Vp+Vop, where the Vcom, the Vp and the Vop denote a commonvoltage applied to the common electrode, a voltage applied to a pixelelectrode, and a voltage generating an electric field by the operationof the switching panel, respectively.

A voltage Vop (=V2−Vp) is generated when a voltage applied to the firstcommon electrode Vcomp1 is V2 and the voltage applied to the pixelelectrode is Vp. Thus, the light is transmitted by means of the electricfield (R1 region). However, when the voltage applied to the secondcommon electrode Vcomp2 is V1 which is equal to the voltage Vp appliedto the pixel electrode, the electric field is generated between thecommon electrode and the pixel electrode so that the transmissivity is 0(R2 region).

The parallax barrier pattern is thus formed where transmissive regionsand the blocking regions are repeated alternately, and an observerperceives the images and binocular parallax so as see the imagethree-dimensionally.

FIGS. 5A and 5B illustrated an example where that the pattern of thepixel electrode may be modified, while FIGS. 7A to 7C illustrate anexample where the pattern of the common electrode may be modified.

After forming the common electrode such that it is inclined at apredetermined angle (α deg), both edge regions thereof may be patternedin shape of a step. Herein, a denotation C1 means the width of the firstcommon electrode Vcomp1, a denotation C2 means a distance between stepsin the common electrode, and a denotation C3 means the width of adjacenttwo common electrodes, i.e., the first common electrode 153 a and thesecond common electrode 153 b. Each common electrode is inclined at thepredetermined tilt angle (α deg).

The first and second common electrodes 153 a and 153 b are formed ondifferent layers, respectively, such that the edge portions areoverlapped with each other. Therefore, there is no separation distancetherebetween in a plan view.

FIG. 7B illustrates a common electrode structure in which the commonelectrodes are inclined at the predetermined tilt angle (α deg) withoutthe step structure, of FIG. 7A. FIG. 7C illustrates a common electrodestructure in which the common electrodes having an equal size are formedin parallel without a tilt. C6 is the width of each common electrode

FIG. 7B illustrates a common electrode structure in which the commonelectrodes are inclined at the predetermined tilt angle (α deg) withoutthe step structure, of FIG. 7A. FIG. 7C illustrates a common electrodestructure in which the common electrodes having an equal size are formedin parallel without a tilt. C6 is the width of each common electrode

As described above, by variously forming the common electrode pattern ofthe switching panel, the parallax barrier pattern is formed in variousshapes so that it is possible to enhance an image quality of the adisplayed 2 or 3-dimensional image. Therefore, the tile angle, width, orpattern shape of the common electrode may be selectively applied to eachdisplay device according to the size of the display device and a kind ofdisplayed image.

In addition, when forming the common electrode in various shapes, thetransmissivity characteristic over a range of viewing angles is improvedso that it is possible to reduce the color change phenomenon as afunction of viewing angle.

The pixel electrode patterns of FIGS. 5A and 5B, and the commonelectrode pattern of FIGS. 7A to 7C may be applied to the switchingpanel, respectively or simultaneously.

FIG. 8 is a schematic showing the formation of the parallax barrierpattern of the switching panel. The parallax barrier pattern is formedby forming the transmissive region R1 and the blocking region R2, whichare illustrated in FIG. 6.

FIG. 9A is a graph illustrating a color change versus a viewing anglewhen using the related art switching panel, and FIG. 9B is a graphillustrating a color change versus a viewing angle when using theswitching panels described herein. When applying the switching panelhaving the TN mode electrode structure according to the related artdisplay device, that the color change becomes large over a range of theviewing angles.

As shown in FIG. 9B, the color change over a range of viewing angles issmaller, when using switching panel having the IPS or FFS mode structurein which the pixel electrode and the common electrode are formed on thelower substrate The tilt angle ranges from 5° to 12° and the distancebetween the electrodes is about 3.2-4.2 μm. The angle for the optimumtransmissivity characteristic may vary according to the size of thepanel, the liquid crystal, the electrode width, and the distance betweenthe electrodes.

As described above, when forming the pixel electrode pattern or thecommon electrode pattern, the transmissivity characteristic may beenhanced so as to improve the image grade of the display device.

Although only a few examples of this invention have been described indetail above, those skilled in the art will readily appreciate that manymodifications are possible without materially departing from the novelteachings and advantages of the invention. Accordingly, all suchmodifications are intended to be included within the scope of thisinvention as defined in the following claims.

1. A display device comprising: an image display panel including a colorfilter layer and a thin film transistor layer; a switching panelincluding upper and lower substrates with a liquid crystal layerinterposed therebetween; and a backlight unit disposed more distal froman observer than the image display panel or the switching panel, whereina pixel electrode, and first and second common electrodes are formed onthe lower substrate and apply an electric field to the liquid crystallayer, wherein the first and second common electrodes are formed ondifferent layers, respectively, wherein the first and second commonelectrodes are partially overlapped, and wherein the pixel electrodecomprises a transparent conductor, and the first and second commonelectrodes comprise an opaque conductive material.
 2. The display deviceof claim 1, wherein the upper substrate is a glass substrate.
 3. Thedisplay device of claim 1, wherein the pixel electrode is formed suchthat it is inclined at a predetermined angle with respect to analignment direction of an alignment layer formed on the lower substrate.4. The display device of claim 3, wherein an angle between the pixelelectrode and the alignment direction is in a range of 3° to 5°.
 5. Thedisplay device of claim 1, wherein the first and second commonelectrodes are formed such that they are inclined at a predeterminedtilt angle with respect to an alignment direction of an alignment layerformed on the substrate.
 6. The display device of claim 1, wherein thefirst and second common electrodes have different widths.
 7. The displaydevice of claim 1, wherein the first and second common electrodes havestep-shaped structures.